• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.82-84
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• 2020

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.643-650
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• 2017

The control of flexible joint robot is getting more attentions because its applications are more frequently used for robot systems in these days. This paper proposes a robust impedance controller for the flexible joint robot by using integral sliding mode control and backstepping control. The sliding mode control decouple disturbances completely but requires matching condition for disturbances. The dynamic model of flexible joint robot is divided into motor side and link side and the disturbance of the link side does not satisfy matching condition and cannot be decoupled directly by the actual input in the motor side. To overcome this difficulty, backstepping control technique is used with sliding mode control. The mismatched disturbance in the link side is changed into matched one in the respect to virtual control input which is the state controlled by actual input in the motor side. Integral sliding mode control is used to preserve the impedance control performance and the improved robustness at the same time.

• Journal of IKEEE
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• v.24 no.1
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• pp.154-160
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• 2020

This paper presents a grid current control algorithm for a grid connected inverter (GCI) system in a stationary reference frame. When a Proportional Integral (PI) controller at a stationary reference frame is used in a GCI system, steady state error and phase lags are presented because AC signals are controlled at a stationary reference frame. In this paper, a feedforward controller is applied to the PI controller to compensate the steady state error and phase lags by improving command tracking performance. In addition, disturbance rejection control is applied to the PI controller to protect the GCI system by eliminating disturbance, grid voltage in a GCI system, when a grid fault such as line-to-line fault, happens. The proposed GCI current control algorithm is analyzed in a frequency domain and a simulation model of the proposed GCI current control system is developed for verification of the performance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.89-93
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• 2000

Robust control for DC motor is needed according to the highest precision of industrial automation. However, when a motor control system has an effect of load disturbance, it is very difficult to guarantee the robustness of control system. Generally, it is known that sliding mode controller has robustness. But, after it is assumed that we known the disturbance uncertainty, sliding mode controller is designed. Thereafter, if we are not known th disturbance uncertainty then controller design is difficult. As a method solving this problem, in this paper, Expert sliding mode control method for motor control system is presented.The proposed controller can eliminate load disturbance effectively. The effectiveness of the control scheme is verified by simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.627-634
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• 1998

This paper proposes an algorithm which improves capacity of a state observer and low speed driving characteristics of a induction motor by inertia moment identification. In induction motet driving systems, it is difficult to obtain the accurate speed information by a low resolution encoder because the encoder pulses are very few in a low speed range. To improve this problem, state observer based on the Gopinath' theory which estimates speed and disturbance was designed, and disturbance rejection control was realized by application of the observer. Also, inertia moment of the motor was estimated and the nominal inertia of the observer was identified to minimize the error of estimated speed and disturbance. From the simulation and experimental results, it is showed that the proposed observer improved the transient response characteristics in low speed region below 6［rpm］.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2658-2661
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• 2004

압전 구동기는 전기적 에너지를 직접 동역학적 에너지로 변환하는 세라믹 구동기이다. 특히 압전 구동기의 개방 회로 시스템은 분자 구조 특성에 의해 비선형적인 히스테리시스 특성과 크리프 특성을 가진다. 이러한 비선형적 시스템을 작은 분해능으로 제어하는 경우 이에 따른 외란, 모델링의 불확실성 둥의 오차가 발생하게 된다. 따라서, 현재 이러한 비선형적 오차를 기존의 PID 및 최적제어를 사용하여 보상하는 방법에 대해서 많은 연구가 진행되고 있다. 본 논문에서는 압전 구동기 위치 결정 시스템 전체에 대해 LQG 제어 및 $H_{\infty}$ 제어를 적용하여 시뮬레이션을 실시하였다. 또한 본 논문은 시뮬레이션 결과를 바탕으로 실제 압전 구동기 위치 결정 시스템에 $H_{\infty}$ 제어를 적용하여 제안된 $H_{\infty}$ 제어기가 시스템 성능에 영향을 주는 외란, 모델링의 불확실성 등을 효과적으로 제거함을 보여준다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.64-69
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• 2009

In this paper, we evaluate a performance on a transmission power control algorithm in a SIR-based wireless networks. We consider the existing iterative power control algorithms into a unified dynamic state system formulation in both continuous-time and discrete-time system. Numerical experiments are performed under the disturbance of sinusoidal. These results indicate that the proposed power control scheme has a performance improvement with a better disturbance elimination in wireless mobile systems.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.2
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• pp.109-114
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• 2001

본 논문에서는 비선형 제어시스템의 성능 개선을 위한 새로운 신경망 직접 적응제어 알고리즘을 제시하였다. 제어칙은 Gaussian RBF 신경망을 이용한 제어입력과 근사화 오차 및 외란의 영향을 제거하기 위한 보조제어 입력으로 구성하였다. 또한 신경망에 사용된 가중치와 보조입력의 파라미터를 조정하기 위한 적응칙은 Lyapunov 안정도 이론에 의하여 구하였다. 이렇게 함으로써 외란이나 근사화 오차에 관계없이 플랜트와 기준모델 사이의 오차가 0이 되도록 하는 알고리즘을 구할 수 있었다. 또한 제시된 알고리즘의 효용성을 알아보기 위하여 Duffing forced oscillation 시스템에 대하여 시뮬레이션 하여본 결과 만족할만한 성능을 얻을 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1597-1600
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• 2010

In this paper, a direct controller for nonlinear plants using a neural network is presented. The composed of the control input by using RBF neural networks and auxiliary input to compensate for effects of the approximation errors and disturbances. In the results, using this scheme, the output tracking error between the plant and the reference model can asymptotically converge to zero in the presence of bounded disturbances and approximation errors. Simulation results show that it is very effective and can realize a satisfactory control of the nonlinear system.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.153-157
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• 2002

일반적으로 가변구조제어는 외란과 변수 변화에 대해 강인한 특성을 가지지만 제어기 설계자는 이러한 값들에 대한 상한 값과 하한 값을 알아야한다. 그러나 때로는 이러한 상한 값과 하한 값을 얻는다는 것은 쉽지가 않다. 이에 반해 퍼지제어기는 외란과 변수 변화에 대한 제어기 설계에 있어서 효과적인 방법을 제공한다. 따라서 퍼지제어기와 가변구조제어기가 가지는 장점들을 결합하는 연구가 진행되어져 왔다. 본 논문에서는 리칭페이저가 존재하는 기존의 슬라이딩모드제어기를 이용하는 방법 대신 리칭페이저를 제거하여 전 구간 강인한 적응 퍼지 가변구조제어기를 설계하였다. 제안된 제어 알고리듬은 BLDC 전동기의 위치제어기로 사용하였으며, 그 타당성을 입증하였다.